A cohort of 3,367 substance abusers seeking treatment were administered measures of aggression and hostility including the Buss-Durkee Hostility Inventory and the NEO Personality Inventory Hostility Scale. Polysubstance abusers scored significantly higher on all measures of hostility and aggression, regardless of whether they abused cocaine or not. Subjects scoring higher on aggression and hostility utilized escape-avoidance, distancing, and confrontational coping styles more regularly. Subjects scoring higher on measures of aggression and hostility reported more situations that triggered their use of substances and less confidence that they could resist using when faced with such situations in the future. This was especially true for situations involving unpleasant internal states, situations involving rejection, and situations involving conflict with family and friends. The implications of these findings for clinical assessment and treatment planning are discussed.